Interfacial engineering of poly (lactic acid) composite films using esterified cellulose nanocrystals/curcumin hybrid nanofiller for improved mechanical and antibacterial performance.

Polylactic acid (PLA), as a biodegradable material, is considered an ideal alternative to petroleum-based plastics. The intrinsic mechanical fragility and lack of multifunctional characteristics significantly constrain its practical utilization in advanced applications. This study designed and prepared a ternary PLA composite material with uniform surface and enhanced functionality by uniformly dispersing esterified CNC (EnCNC) Curcumin (Cur) hybrid nanostructures in the polymer matrix. The synergistic interaction between the EnCNC and Cur significantly enhanced their interfacial compatibility with the PLA matrix, leading to uniform dispersion and significantly improved flexibility. The flexibility of resulting EnCNC_Cur_PLA composite films was significantly improved, with elongation at break increased to 64.42 %, representing a 628.59 % increase compared to pure PLA. The addition of EnCNC increased the bioavailability of Cur and demonstrated multifunctional effects, including controlled release of Cur in ethanol, enhanced antioxidant activity (80.6 % DPPH clearance) and antibacterial activity (over 99 % against Escherichia coli, 87.7 % against Staphylococcus aureus). Overall, these results highlight a simple and effective strategy to fabricate multifunctional, sustainable bio-based films with improved mechanical performance and biological activity, suitable for advanced food packaging applications.